Heat makes emergency rooms busier. Study shows which illness and injuries rise during hot spells

A recent study of Chicago hospital and urgent care records spanning 2011 to 2023 shows that when temperatures reach 92.6 degrees Fahrenheit or higher, emergency rooms and urgent care centers experience a surge in visits. Researchers from Northwestern University analyzed data from 916,404 visits and found that more than a dozen categories of injuries and illnesses become more frequent during hot spells.

These include accidental gunshot wounds, kidney complaints, skin problems, varicose veins, and mental health issues related to marijuana use.

While the study focused on Chicago, experts outside the research highlighted its implications for the broader warming world. Dr. Abel Kho, the study's senior author and an internal medicine professor at Northwestern, described hot days as "something's going to happen," emphasizing the likelihood of external injuries and complications of certain conditions during heatwaves.

Some problems, such as accidental gunshot wounds and cannabis-related mental health issues, saw dramatic increases, with some jumping more than 30-fold compared to cooler days.

Dr. Jonathan Patz, chair of health and environment at the University of Wisconsin, stated that the study confirms the underestimated health risks from heat exposures. Dr. Courtney Howard, a Canadian emergency room physician and president-elect of the Canadian Medical Association, noted that the study serves as a reminder that the price of climate change includes increased illness, strain on the health care system, and higher health care costs.

The researchers acknowledged that heat-related illness is often undercounted when studies focus solely on explicit heat codes like heat stroke. They found an association between high temperatures and individual medical problems but emphasized that this does not equate to a cause-and-effect relationship. The study's data showed a higher representation of Black people and women compared to the general population, which is a positive aspect given the underrepresentation of these groups in medical studies.

Dr. Nicholas Cozzi, president-elect of the Illinois College of Emergency Physicians, pointed out that the study's findings have important implications for the public. He advised that people, especially those with chronic conditions such as kidney disease, multiple sclerosis, and venous issues, should take extra caution on extreme heat days. Additionally, he stressed the importance of being mindful of the potential increased effects of medications like cannabinoids when exposed to heat.

Interestingly, while cardiovascular problems are commonly connected to heat in other studies, this research did not find a significant spike in cardiovascular issues during hot days. Dr. Kho suggested that this might be because individuals with cardiovascular problems often have other conditions, such as kidney or fluid issues, which influence how their medical records are coded.

Dr. Howard explained that dehydration or changes in fluid status can contribute to cardiovascular disease as the heart works harder to pump more concentrated blood to support sweat-related cooling mechanisms.

Overall, the study underscores the real effects of heat waves beyond mortality, extending to morbidity and various other health issues. It serves as a reminder that the price of climate change includes increased illness, strain on the health care system, and higher health care costs.